Nice.You can see mine here about a year ago. (the only nep besides sanguinea) http://img208.imageshack.us/img208/3977/1010984ir9.jpg
Perhaps it is the extra light causing the leaves to shrink as xvart suggested and with the extra heat there is less humidity causing the pitchers to shrivel? Just a guess.
I have read that increasingly smaller leaves can be caused by root rot as well which is why I suggested the media being water logged and/or rotted. It was hard to tell from your pic, but it did look rather dark. But the peat perlite mix explains that.